Oscilloscope and its circuit



Jan. 9, 1951 SAW TOOTH VOLTAGE GENERATOR RQJ. URICK ETAL OSCILLOSCOPEAND ITS CIRCUIT Filed April 1, 1946 ELECTRICAL OSCI LLATO R VOLTAGE DIV}DER SWEEP GENERATOR LOW FREQUENCY DEFLECTION AMPLIFIER ISOLATING FILTERNET- 4 7 WORK SIGNAL SOURCE TO BE OBSERVED DEFLECTION AMPLIFIER aISOLATING 6 FILTER LOW FREQUENCY NETWORK AND SIGNAL INVENTORS ROBERT J.URICK ROBERT M SHERWOOD Attorney Patented 'Jan. 9, 1951 UNITEDOSCILLOSCOPE AND ITS CIRCUIT Robert J. Urick and Robert M, gherwood, SanDiego, Calif.

Application April 1, 1946, Serial No. 658,722

"4 Giaims. (cl. 315-24) (Granted under the act of March 3, 12383, asamended April 30, 1928; 370 0. G. 757) Our invention relates to systemsfor recording electrical phenomena on a photographic film.

It has been the practice in this art to use an oscijllograph to recordthe desired electrical signals, which may be recurring or transient, andthen by means of a lens to permanently record this data on aphotographic film, which may be either continuously running or of thesingle ex posure type. In the continuously running method, a veryaccurate film drive is required in order to have a linear time base andto prevent distortion of applied signals. Another disadvantage is thelarge amount of film needed in order to record the data along a movingtime base and to be sin-e the film is running when the desired transientelectrical phenomenon occurs. In the single exposure type film,extremely accurate timing is required in order to expose the film justas the electrical phenomenon occurs. In some cases where the occurrencetime is not known, this method would be impossible. second disadvantageof this method is the short recording time, limited by the period of onehorizontal sweep on the oscillograph.

Our invention uses a continuously running film, in which n(approximately 5-15) lengthwise traces are recorded for each traceacross the film. This is possible because of the higher frequency of thetime-base sweep voltage applied to the oscillographs deflecting plates.Recording for a long period with a minimum of distortion, and goodresolution of wave shape (due to fast sweep) are hereby obtained.

In accordance with our invention, a continuously moving photographicfilm is used to permanently record for a desired amount of time theelectrical data presented on an oscillograph.

Further in accordance with our invention, the vertical time base of the.oscillograph is broken up numb r of tim s Whi being swept h izontally,.so as to use approximately 1 /n the length of film ordinarily required.

Our invention further resides in systems hav-.- ing features hereinafterdescribed and claimed.

:For an und rstand n of our invention a r illustration of examplesthereof, reference is made to the accompanying drawing, in which thefigure is block diagram of the electrical system, showing theoscillograph and photographic equipment.

"In the figure, the electrical oscillator I (at 1 cycles per second) ofhigh frequency reliability and tability supplies a voltage used tosynchro- 112.6 the entire system and to provide an accurate the amplifir 3 i a voltag div der 4 used o syn ohromao a sawtooth. o age gene a orof /n f y s Pe second. where .n is int ger in the order o 5 15- Theutput at the lo fr que a oth, generator is applied through an isolatingfilter network i, and deflection amplifier 8 to the hori- Zontal Platestil. Th sou ce of he signal to be observed 6, which may be a singlerandom volta e o a mixed utput o s ra uc vo ages, is applied through anisolating filter network 12 and deflection amplifier 8 to the horizontalplates of the oscilloscope 9.

The natu e of the attern iormo o th .ia e oi the soillog epb 9 by theoutputs of amp fie s 3 and 8 i sh wn The spot ta ts at the wer ef a d moe upwa d. at a a ontrolled b e irooueno oi generato .2 and at h s metime moves slowly to the right at a rate conrolled by the frequen y ofene ato 5- A it moves right at frequency l/nxf, it also moves up anddown at frequency 1. Any signal I3 com, in n pp rs as a ho izontaldeflection. T decay rate of the phosphorescence oi the tube 9 is high soas t9 avoid blurring of the photographic recpi'd. Since the fiy-backtime of sweep generators 2, 5 is extremely small, the pattern on he tu epro des a virtu ll contin o s r o d of the incoming signal voltage 6.

The photographic lens l 0 is of large aperture,

suitable for work with narrow film H, such as 35 .or 16 mm. movie film.The oscillograph 9 and film II are at conjugate -foci with a linearmagnification of M times. (M is less than unity.)

A section of film H is carried past lens ii! at a, constant though notnecessarily accurately known speed. As the film moves upward the latentimage of successive vertical lines of the origina'l pat rn omes regularldisplaced wn.- ward.

The film movement and operating sawtooth frequencies are adjusted sothat the film movement D in 12/! seconds (period of generator 5 sweep)is slightly more than the length of the oscilloscope screen trace htimes the magnification M. In this way a continuous record of the signal6 is obtained with the expenditure of only slightly more than l/n of thefilm which would otherwise be required to secure equal detail.

-duration. phenomenon occurs can be accurately measured because eachvertical'sweep represents l/f seconds. Thus an accurate time base isavailable for measuring voltage or current differentials with respect totime.

For a clearer understanding of our invention,

. numerical examples of. our improvements are.

given.

1. For a given frequency response or ability to study transients of veryshort time occurrence, our invention needs only 300 or less feet of filmto cover a 10 minute observation and without interruption or breaks,whereas a conventional system would require approximately 3000 feetoffilnL In any measuring system, assume that transients occur in onemillisecond and observations must cover 10 minutes, and .06" of film isminimum length which can be studied to see what occurs in any given onemillisecond interval.

vIn known systems where V1=velocity of, film, D=distance film travelled,and T=time of film to travel D:

For 10 minutes, this known system would need D1 feet of film, where V=60 inches/sec.=5 feet/sec.

In our invention, assume v (vertical sweep frequency) =15 cycles, lengthof screen=4= inches. and n (number of vertical sweeps on one horizontalsweep)=l2. Then, where Th=period of one horizontal sweep, fh=horizontalfrequency:

length of screen+0.5 clearance f time for one horizontal sweep 4.5inches 0.8 second For ten minute observation, film travel would be 5.6inJsec. lO'XGO 2 Factors such as optical magnification affect bothsystems equally, and so are omitted.

T (period of horizontal scope V;'=4:.5 Xf f, (frequency of verticalsweep 7 generator) j,=; i inches/sec. 12=l60 cycles/second T 6.25milliseconds V, (vertical sweep velocity) 4 (actual length of scope)inch .00625 .O0l sec.

. I I (minimum amount of space required V for accurate study) .001 a;(time interval while time base moves .06 in our invention) w= .094millisecond 1.000 millisecond '10.6 or

.094 millisecond 1 approximately 11:1

(The magnification factor M is omitted, since it acts both in knownsystems and in my invention.)

3. As the vertical velocity is much greater than the films velocity, thetime base on which any signal is measured is essentially that timingdetermined by the vertical sweep voltage. The film moves aninsignificant distance during each vertical sweep; so its velocity (anddegree of accuracy thereof) is not important in the measurement of time.This permits use of simple film drives whose speed regulation is notcritical. This affects savings in weight and power.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. In a system for ph'otographically recording on a continuously movingfilm, oscillograph traces resulting from electrical signals; asynchronizing voltage generator of f frequency, a cathode rayoscilloscope, a sawtooth voltage generator activated by saidsynchronizing generator, the sawtooth voltage being applied to thevertical plates of said oscilloscope, a sweep generator of f/n frequencyapplied to the horizontal plates of I said oscilloscope, the potentialson the vertical and horizontal plates causing n" oblique traces to beproduced for each horizontal sweep, a first deflection amplifier beinginterposed between the sawtooth voltage generator and the verticalplates of said oscilloscope, a second deflection amplifier beinginterposed between the sweep generator and the horizontal plates of saidoscilloscope, said sweep generator being initiated by a portion of theoutput of the above-mentioned first deflection amplifier, a source ofsignal to be observed, sig nals from said source being injected into theinput of said second deflection amplifier along with the output of thesweep generator.

2. In a system for photographically recording on a continuously movingfilm, oscillograph traces resulting from electrical signals; asynchronizing voltage generator of 7 frequency, a cathode rayoscilloscope, a sawtooth voltage generator activated by saidsynchronizing generator, a first deflection amplifier in seriesrelationship with said sawtooth generator and connected to the verticalplates of said oscilloscope, a sweep generator of f/n frequencyconnected to the first deflection amplifier and initiated by a portionof the output of said first deflection amplifier, a second deflectionamplifier in series relationship 'with said sweep generator andconnected to the horizontal plates of said oscilloscope so that 'noblique traces are produced for each horizontal sweep, a source ofsignal to be observed, said sig.-'. nal being inserted at the input ofsaid second 'de flection amplifier to produce horizontal irregularitiesalong the oblique traces.

3. In a system for photographically recording on a continuously movingfilm, oscillograph traces resulting from electrical signals; a cathoderay oscilloscope, means for effecting vertical deflections on saidoscilloscope at a predetermined frequency, means for effectinghorizontal deflections at a frequency integrally related to the verticaldeflection frequency to produce a plurality of oblique traces, a sourceof signal to be observed, said Signal being inserted in parallel withthe horizontal deflecting frequency to produce irregularities along theoblique traces.

4. In a system for photographically recording on a continuously movingfilm, oscillograph traces thereby producing irregularities on saidoblique traces in conformance with said signal.

ROBERT J. URICK. ROBERT M. SHERWOOD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 650,096 Rodde May 22, 19002,178,471 De Bruin Oct. 31, 1939 2,227,135 Holhnan Dec. 31, 19402,293,135 Hallmark Aug. 18, 1942 2,307,505 Heinmetz Jan. 5, 19432,402,168 Lifschutz June 18, 1946 2,405,238 Seeley Aug. 6, 19462,444,341 Easton June 29, 1948 2,448,762 Beste Sept. 7, 1948 2,465,355Cook Mar. 29, 1949 2,489,253 Andre Nov. 29, 1949 2,501,352 Opsahl Mar.21, 1950

